When sailing a device with a non-stationary rig attached by a universal joint to the deck, it is required that the sailor hold the rig in position. This includes sailboards, which are basically surfboards anywhere from eight to twelve feet long with a rig attached; and land sailboards, which look like elongated skateboards and are used on smooth land. The nature of sailboards requires that they be sailed most frequently on a reach. To accomplish a reach the sailor must position the rig so as that his back is facing the wind. Holding the rig in an upright position by the boom requires the sailor to pull towards himself as well as towards the stern of the board so as to create forward momentum. The force applied by the sailor often needs to be quite strong and must be continuous. Providing this force is done primarily be leaning backward and using the mass of the body to counteract the the force of the wind. The actual grasping of the boom by the hands must therefore bear the brunt of the fatigue. Fingers must stay tight around the boom for extended periods of time which can, on particularly windy days, cause muscle fatigue in the muscles in the forearm.
At this point in time the current method of alleviating the fatigue is done by use of a chest, waist, or seat harness. Here a hook is attached to a body harness. A line is attached to the boom so as that if forms a semi-loop centered over the center of pull necessary to keep the rig in proper position. The sailor then bends to engage the hook in the line and then leans with the majority of his weight on the harness system leaving a little of the weight to his hands so as to allow him to steer and adjust. This system is widely used and is fairly successful but has its disadvantages. The harness must be disengaged when jibing, tacking, and most importantly: falling. If under control the harness is easy to disengage where then the sailor uses only his hands to guide the rig during say a jibe. When hit by a gust, lull, lift, or knock when the system is engaged, however, disengaging becomes more difficult. It often results in the sailor being thrown dangerously into the sail and/or the boom. The sailor can also become trapped under water by the sail and is still attached to the boom by the harness line that has twisted around the hook. Body harnesses can be even more dangerous when used with a land sailboard; dangerous to the point where they are rarely used.